This invention represents an improvement over such apparatus as disclosed in U.S. Pat. No. 3,960,094 issued June 1, 1976 to James C. Hsiao. However, the invention is equally applicable at least in part, to other types of sewing machines having article orientating mechanism means.
In rotational button indexers of the type described in the above identified patent, it is necessary to provide means for engaging and orientating a button prior to the latter being sewn. Upon completion of the sewing cycle the orientating means needs to be removed or disengaged from the button and lifted a sufficient distance from the indexer so as to allow the button turret to rotate the orientated button into the sewing position.
To facilitate disengagement of the orientating means from the button as well as to maintain the orientating means a sufficient distance from the indexer there has been disclosed in the above mentioned patent a flat spring pivotally mounted on the button clamp of the machine. One end of this spring is constrained in a vertical plane while its second end is in engagement with the orientating means. When the clamp is moved to its raised position the end of the spring engaging the orientating mechanism will be forced upward a sufficient distance to disengage the orientating mechanism from the button and securely maintain the orientating mechanism in a raised position away from the button turret. However, an embodiment of this sort has certain drawbacks. One of these drawbacks is that when the button clamp is raised at the end of the sewing cycle it moves with a velocity such that it overthrows its raised position and is forcibly returned slightly downward by a suitable spring mechanism means. The spring back motion of the clamp imparts an identical spring back motion to the leaf spring carried thereby. The spring back motion imparted to the leaf spring causes the orientating means and more particularly the pins depending therefrom to forcibly strike the top of the button turret thus causing damage to same. In order to overcome the spring back problem inherent with the leaf spring design a preload stress was applied to the second end of the spring so as to hold the orientating means in a position removed from the button turret when the clamp was raised. The preload stress placed upon the leaf spring caused further problems in that this stress caused considerable wear and breakage of the leaf spring. The preload stress also caused the orientating means to bear on the bottom of the clamp when the latter was in the raised position. The orientation of the button indexer occurs when the button clamp is in the raised position and the bearing of the orientating means on the underside of the clamp means added frictional stresses to the indexing mechanism.
To maintain the desired result of keeping the orientating means in a position removed from the button indexer, it has also been proposed in the art to use a spring displaced between the button clamp and the orientating means for holding the latter in a proper position upon completion of a sewing cycle. A drawback similar to that inherent with the leaf spring previously discussed results. That is, when the clamp is lifted and is instantly stopped, a resonance in the spring results thus, the pins depending from the orientating mechanism will contact the top of the button turret and after repeated occurances cause considerable wear thereon.